Thermionic tube



July 16, 1935. JQBST 2,008,505

THERMIONIC TUBE Filed Sept. 17, 1952 INVENTOR GUNTHER J 5T Patented July 16, 1935 UNITED STATES THERMIONIC TUBE Gunther Jobst, Berlin, Germany, assignor to I'elefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany, a corporation of Germany Application September 17, 1932, Serial No. 633,559 In Germany September 11, 1931 6 Claims.

This invention relates to thermionic tubes, and more particularly to that type wherein the transition between the rectilinear steep part of the working characteristic and the substantially horizontal part thereof occurs at a very slow and gradual rate. These tubes are especially suited as radio frequency amplifiers in arrangements wherein, by the variation of the grid biasing potential, the gain is to be altered or controlled. Owing to the slow change from the steep and straight part of the working characteristic into the horizontal part thereof, it is possible to operate the tube at points presenting and insuring widely dissimilar amplifying powers without there arising marked distortions resulting from the unduly marked curvature of the characteristic. In the arrangements heretofore known, tube characteristics of the said sort have been realized by the use of a grid electrode in which the distance between adjacent grid turns was changed along the filament or in the direction of the filament axis. 7

According to the present invention a tube arrangement of simple construction is created by that, while the filament is disposed symmetrically in reference to the plate or anode electrode, the grid is arranged or constructed dissymmetrically in a plane at right angles to the filament. In this manner the grid characteristic in longitudinal direction can be made uniform so that by suitable choice and dimensioning of the electrodes in longitudinal sense tubes of varying saturation current and accordingly different internal resistance can be produced.

Figs. 1 to 4. illustrate some feasible embodiments of an electron tube arrangement according to the present disclosure, the same showing a cross-section of the tube at right angles to the electrodes. The trans-grid action of the plate or anode electrode (reciprocal gain) is not uniform in the plane of the section, indeed, it differs according to the azimuth. By the superposition of partial characteristics of different inclination as shown in Fig. 5 wherein the abscissa represents g id voltage (Eg) and the ordinate represents plate current (Ip), a tube is thus obtained whose aggregate characteristic as the sum total of the partial characteristics does not fulfill the E law, but which exhibits a far less marked slope. In 50 the longitudinal axis, as already pointed out, the discharge conditions are similar so that the tube disposition as described has properties of cylindrical symmetry.

Fig. 1 shows a cross-section view of an amplifier tube in which the filament K and the anode A are disposed co-axially in reference to each other. The anode consists of a circular cylinder. The control grid G is eccentric in the form ofa broken (apertured) body of elliptic cross-section.

In the embodiment shown in Fig. 2 the control grid G is likewise arranged co -axially in relation to the filament and the anode, though on one side the spacing between grid-meshes is chosen closer than upon the other side of the grid.

Similar discharge systems are shown in Figs. 3 and 4 wherein, in lieu of a circular cylindrical anode cylindrical anodes of elliptical form conjointly with a plurality of filaments are used.

I claim:

1. A thermionic tube comprising a cathode, an

anode surrounding the cathode, and a perforated grid electrode interposed between the cathode and the anode, the number of perforations on one side of the grid along its length being greater than that on the other side of said grid.

2. A thermionic tube comprising a cathode, a perforated grid surrounding the cathode, and an anode electrode surrounding the perforated grid,

the number of perforations on substantially onehalf the surface of the grid along its length being greater than that on the other half grid surface.

3. A thermionic tube comprising a flattened cylindrical perforated grid electrode, an anode surrounding the grid and a cathode disposed within the grid, the opposing faces of said grid electrode being provided with totally different numbers of perforations.

4. A thermionic tube comprising a cylindrical anode, a cathode within the anode and concentrically mounted with respect thereto, and a grid electrode surrounding the cathode but eccentrically mounted with respect to both cathode and anode.

5. A thermionic tube comprising a cylindrical anode, a cathode within the anode and concentrically mounted with respect thereto, and a grid electrode surrounding the cathode but eccentrically mounted with respect to both cathode and anode, said grid electrode having on substantially one-half of its surface along the length of the grid a greater number of perforations than on the other half grid surface.

6. A thermionic tube comprising concentrically mounted cathode, grid and anode electrodes, the grid electrode being perforated'and the number of perforations on one side of the grid along its length being greater than that on the other side of said grid.

GU'NTHER J OBST. 

